1. Field of the Invention
The present invention relates generally to internal combustion engines and, more particularly, concerns a protective device which automatically shuts down an engine having two banks of cylinders and an associated cooling circuit for each bank in the event of inadequate coolant flow to either bank of the engine. The present invention is especially suitable for use in certain dual-sided diesel locomotive engines.
2. Description of the Prior Art
Many internal combustion engines employ a closed, pressurized cooling circuit to permit engine operation at elevated temperatures and pressures. Such cooling circuits typically include: a coolant fluid; a pump which circulates the coolant through the engine by increasing its pressure; and a radiator which reduces the temperature of the coolant after it has passed through the engine so that it may be recirculated through the engine.
Since engine damage can be prevented or minimized if engine operation is terminated should there be a malfunction in the cooling circuit, several protective devices have been developed which are well known in the art. Typically, these devices monitor designated pressures within the cooling circuit and activate an alarm or an engine discontinuation mechanism if coolant pressures deviate significantly from normal. In an exemplary protection device, failure of a cooling pump could cause a pressure aberration sufficient to trigger an engine shut down or actuate an alarm.
Such devices, however, often suffer from a number of shortcomings, including the inability to function properly if they are used in conjunction with more than a single cooling circuit. For example, U.S. Pat. No. 3,958,548, issued to Koci et al. on May 25, 1976, discloses an engine protective device for use in an engine with a single cooling circuit. In particular, Koci teaches an apparatus which utilizes a diaphragm-type detector device to continuously monitor the inlet and outlet pressures of the cooling pump, as well as the pressure in the engine airbox. Engine operation is discontinued if the pressure differential across the cooling pump becomes less than the airbox pressure. Koci does not disclose the use of more than a single cooling circuit, nor does the Koci patent disclose the use of an apparatus to connect an additional cooling circuit to the detector. Indeed, to adequately protect a diesel locomotive engine with two banks of cylinders and having a cooling circuit associated with each bank, two Koci diaphragm detector mechanisms would be required, one for each bank. On the other hand, should a single Koci device be connected to one circuit of an engine having two cooling circuits, and should there be a failure in the unconnected circuit, the detector will not monitor the pressure gradient across the failed pump, engine operation will not be discontinued, and the engine will likely overheat and suffer damage.